src/test/java/com/android/tools/r8/ir/optimize/uninstantiatedtypes/SynchronizedMethodTest.java

// Copyright (c) 2019, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

package com.android.tools.r8.ir.optimize.uninstantiatedtypes;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertSame;

import com.android.tools.r8.NeverInline;
import com.android.tools.r8.TestBase;
import com.android.tools.r8.utils.StringUtils;
import com.android.tools.r8.utils.codeinspector.ClassSubject;
import com.android.tools.r8.utils.codeinspector.CodeInspector;
import com.android.tools.r8.utils.codeinspector.InstructionSubject;
import com.android.tools.r8.utils.codeinspector.MethodSubject;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import org.junit.Test;

public class SynchronizedMethodTest extends TestBase {

  @Test
  public void test() throws Exception {
    String expectedOutput = StringUtils.lines("In A.m()", "Got NullPointerException");
    CodeInspector inspector =
        testForR8(Backend.DEX)
            .addInnerClasses(SynchronizedMethodTest.class)
            .addKeepMainRule(TestClass.class)
            .enableInliningAnnotations()
            .run(TestClass.class)
            .assertSuccessWithOutput(expectedOutput)
            .inspector();

    ClassSubject clazz = inspector.clazz(A.class);
    MethodSubject method = clazz.uniqueMethodWithName("m");

    // The invoke on the uninstantiated turns into a "throw null", and the synchronized method
    // already have a throw instruction in the catch all handler ensuring monitor exit is called.
    List<InstructionSubject> throwInstructions =
        method
            .streamInstructions()
            .filter(InstructionSubject::isThrow)
            .collect(Collectors.toList());
    assertEquals(2, throwInstructions.size());

    // The inserted "throw null" should still be covered by the catch all to ensure monitor exit
    // is called.
    List<InstructionSubject> catchAllCoveredInstructions = new ArrayList<>();
    method.iterateTryCatches().forEachRemaining(tryCatchSubject -> {
      if (tryCatchSubject.hasCatchAll()) {
        catchAllCoveredInstructions.addAll(
        throwInstructions
            .stream()
            .filter(
                throwInstruction ->
                    tryCatchSubject.getRange().includes(throwInstruction.getOffset(method)))
            .collect(Collectors.toList()));
      }
    });
    assertEquals(1, catchAllCoveredInstructions.size());
    assertSame(throwInstructions.get(0), catchAllCoveredInstructions.get(0));
  }

  static class TestClass {

    public static void main(String[] args) {
      try {
        test(new A());
      } catch (NullPointerException e) {
        System.out.println("Got NullPointerException");
      }
    }

    @NeverInline
    private static void test(A obj) {
      obj.m();
    }
  }

  static class A {

    @NeverInline
    static Uninstantiated createUninstantiated() {
      return null;
    }

    @NeverInline
    public synchronized void m() {
      System.out.println("In A.m()");
      A.createUninstantiated().m();
    }
  }

  static class Uninstantiated {
    public void m() {
      System.out.println("In Uninstantiated.m()");
    }
  }
}